I'm told via Twitter that "customers affected should be receiving an email regarding their options", but no reply on whether there will be a follow-up to the message below, because there aren't a lot of options presented here:

So it would appear that both of the UK non-Hive platforms based on AlertMe are going the journey now. I wonder how many customers there were for Safe & Secure? I deliberately never collected any such usage statistics through the Alerty app, so I have absolutely no idea how many there might be. The S&S app stopped working with iOS 10 and I can't find much of an outcry, so perhaps that's pretty telling.

Had a letter through the post last week to say that the Safe & Secure service was being switched off in 30 days from the date of the letter. Letter was dated 9th November, so that makes Saturday 9th December 2017 the switch-off day for S&S - I think we can guess that it'll more likely be the end of Friday 8th or the start of Monday 11th.